fix(frontend): 岗位会商沙箱在 write_file 流式阶段实时打开并刷新

content 先于 path 到达时用临时文件名开沙箱，流式快照改走外部 store 避免整页重渲染卡顿。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-web/src/components/workspace/artifacts/artifact-file-detail.tsx

@@ -121,8 +121,9 @@ function findScrollableArtifactElement(root: HTMLElement | null) {
 
 export function ArtifactFileDetail({
   className,
-  filepath: filepathFromProps,
-  threadId,
+  filepath: filepathFromProps,
+  threadId,
+  mimeType = null,
   onClose,
   allowVirtualMarkdownEdit = false,
   disableDesensitize = false,
@@ -131,6 +132,8 @@ export function ArtifactFileDetail({
   className?: string;
   filepath: string;
   threadId: string;
+  /** Server/tool supplied type wins over path guessing when available. */
+  mimeType?: string | null;
   /** 覆盖默认关闭行为（仅 setOpen(false)）；圆桌 Step3 文件预览用于退出沙箱模式。 */
   onClose?: () => void;
   /**
@@ -150,16 +153,38 @@ export function ArtifactFileDetail({
   const { t } = useI18n();
   const { artifacts, setOpen, select } = useArtifacts();
   const { isMock, thread, publicShareCode } = useThread();
-  const isWriteFileVirtual = useMemo(() => {
-    return filepathFromProps.startsWith("write-file:");
-  }, [filepathFromProps]);
-  const filepath = useMemo(() => {
-    if (isWriteFileVirtual) {
-      const url = new URL(filepathFromProps);
-      return decodeURIComponent(url.pathname);
-    }
-    return filepathFromProps;
-  }, [filepathFromProps, isWriteFileVirtual]);
+  const isWriteFileVirtual = useMemo(() => {
+    return filepathFromProps.startsWith("write-file:");
+  }, [filepathFromProps]);
+  // A streamed tool call can be opened before the path has been normalized by
+  // the artifacts API. Keep the format supplied by the writer so Markdown is
+  // rendered as Markdown instead of falling back to a TEXT source preview.
+  const writeFileLanguageHint = useMemo(() => {
+    if (!isWriteFileVirtual) return null;
+    try {
+      const language = new URL(filepathFromProps).searchParams.get("language");
+      return language === "markdown" ? language : null;
+    } catch {
+      return null;
+    }
+  }, [filepathFromProps, isWriteFileVirtual]);
+  const mimeLanguageHint = useMemo(() => {
+    const normalized = mimeType?.toLowerCase().trim() ?? "";
+    if (normalized.includes("markdown")) return "markdown";
+    if (normalized.includes("html")) return "html";
+    if (normalized.includes("mermaid")) return "mermaid";
+    if (normalized.startsWith("text/")) return "text";
+    return null;
+  }, [mimeType]);
+  const filepath = useMemo(() => {
+    if (isWriteFileVirtual) {
+      const url = new URL(filepathFromProps);
+      return decodeURIComponent(url.pathname).trim();
+    }
+    // Tool arguments may contain harmless surrounding whitespace. Passing it
+    // into extension detection turns `report.md ` into a generic TEXT file.
+    return filepathFromProps.trim();
+  }, [filepathFromProps, isWriteFileVirtual]);
   const isSkillFile = useMemo(() => {
     return filepath.endsWith(".skill");
   }, [filepath]);
@@ -186,17 +211,22 @@ export function ArtifactFileDetail({
   const useWriteFileStreaming = useMemo(() => {
     return isWriteFileVirtual && !isImageFile(filepath) && !editVirtualMarkdown;
   }, [filepath, isWriteFileVirtual, editVirtualMarkdown]);
-  const { isCodeFile, language } = useMemo(() => {
-    if (useWriteFileStreaming) {
-      let nextLanguage = checkCodeFile(filepath).language;
-      nextLanguage ??= "text";
-      return { isCodeFile: true, language: nextLanguage };
+  const { isCodeFile, language } = useMemo(() => {
+    if (useWriteFileStreaming) {
+      let nextLanguage =
+        mimeLanguageHint ?? writeFileLanguageHint ?? checkCodeFile(filepath).language;
+      nextLanguage ??= "text";
+      return { isCodeFile: true, language: nextLanguage };
     }
     if (isSkillFile) {
       return { isCodeFile: true, language: "markdown" };
     }
-    return checkCodeFile(filepath);
-  }, [filepath, useWriteFileStreaming, isSkillFile]);
+    const detected = checkCodeFile(filepath);
+    if (mimeLanguageHint) {
+      return { isCodeFile: true as const, language: mimeLanguageHint };
+    }
+    return detected;
+  }, [filepath, useWriteFileStreaming, isSkillFile, mimeLanguageHint, writeFileLanguageHint]);
   const isSupportPreview = useMemo(() => {
     return (
       language === "html" ||
@@ -209,7 +239,8 @@ export function ArtifactFileDetail({
     // editVirtualMarkdown：用解码后的真实路径走 artifacts API（而非 write-file 虚拟
     // URL），这样保存后 useUpdateArtifactContent 写入的查询缓存才能命中，编辑内容
     // 不会被旧的内存 stub 值覆盖回退。
-    filepath: editVirtualMarkdown ? filepath : filepathFromProps,
+    filepath:
+      editVirtualMarkdown || !isWriteFileVirtual ? filepath : filepathFromProps,
     enabled: isCodeFile && !useWriteFileStreaming,
   });